The present invention relates to a device for transferring cigarette portions.
More specifically, the present invention relates to a device for transferring quadruple cigarette portions, i.e. portions four times the length of the tobacco-filled portion of a finished filter-tipped cigarette, from a manufacturing machine to a filter-assembly machine.
One known method used in the tobacco industry to produce filter-tipped cigarettes comprises forming, on a manufacturing machine, a continuous cigarette rod of tobacco enclosed in a tubular wrapping; cutting double cigarette portions off the cigarette rod, i.e. portions twice the length of the tobacco-filled portion of a finished filter-tipped cigarette; and transferring the double cigarette portions from the manufacturing machine to respective seats on the input conveyor of a filter-assembly machine to connect the filters.
The double cigarette portions are normally transferred using a transfer device comprising a pickup unit for picking the cigarette portions up off the bed of the manufacturing machine; and a supply unit for receiving the cigarette portions from the pickup unit and feeding the cigarette portions, parallel to themselves, to the input conveyor of the filter-assembly machine.
The pickup unit comprises a drum rotating about a respective axis and supporting a number of arms, which are connected to the drum so as to rotate, with respect to the drum, about respective first axes parallel to the axis of the drum, and are each fitted at the free end with a pickup member, which rotates, with respect to the respective arm, about a second axis parallel to the axis of the drum.
Each pickup member comprises an elongated seat with suction holes for retaining a cigarette portion inside the seat, and, in the case of a transfer device used in conjunction with a dual-rod cigarette manufacturing machine, comprises a pair of parallel seats with suction holes for simultaneously receiving a pair of parallel cigarette portions.
The arras are connected to the drum by a first gear transmission for so orienting the arms that the pickup members travel along a substantially elliptical annular path; and the pickup members are connected to the respective arms by a second gear transmission powered by the first transmission and which provides for so orienting the pickup members, with respect to the respective arms, as to keep the pickup members parallel to themselves along said annular path.
The transfer device described advances the pickup members of the pickup unit parallel to the traveling direction of the cigarette portions on the manufacturing machine bed, and along said annular path, which extends about the axis of the drum and is tangent to both the machine bed at a pickup station, and to the outer periphery of at least one roller of the supply unit.
Though used to advantage for transferring cigarette portions between a manufacturing machine and respective filter-assembly machine, the above transfer device involves several drawbacks due to inevitable slack between the gears of said transmissions causing each pickup member to oscillate slightly about the respective axis, thus resulting in misalignment of the respective seat with respect to the respective cigarette portion on the manufacturing machine bed, and in even greater misalignment of the picked-up cigarette portion with respect to the respective seat on the supply unit roller; which misalignments create problems both when picking up and releasing the cigarette portions.
The above drawbacks are further compounded when the device is used for transferring portions longer than double cigarette portions, and in particular for transferring quadruple cigarette portions, which call for longer seats than those normally used for transferring double cigarette portions. That is, for a given degree of oscillation of the pickup members about their respective axes, the above misalignments are proportional to the length of the seats during pickup, and to the length of the cigarette portions during release.